1. Technical Field
The present disclosure relates to a power transmission apparatus for a vehicle.
2. Description of Related Art
A power transmission apparatus for a vehicle that includes a cylindrical case, a breather mechanism, and a support wall has been known. The cylindrical case accommodates a first electric motor, a power split mechanism, and a second electric motor coupled to an output shaft that are lubricated by oil. The breather mechanism communicates between inside and outside of the case. The support wall is provided between the power split mechanism and the second electric motor in the case. The support wall constitutes a first accommodating chamber, in which the second electric motor is accommodated, with an inner wall of the case. In such a power transmission apparatus for the vehicle, the power split mechanism, the first electric motor, and the second electric motor are cooled by the oil in the case. The case, which remains liquid-tight, is provided with the breather mechanism. The breather mechanism is configured to prevent entry of foreign substances and water from the outside of the case while communicating between the inside and the outside of the case, so as to suppress an increase in internal pressure of the case, which is caused by expansion of air and the like therein.
In Japanese Patent Application Publication No. 2009-67140 (JP 2009-67140 A), an accommodating chamber for a first electric motor, an accommodating chamber for a power split mechanism, an accommodating chamber for a second electric motor, and the like communicate with each other via a bearing and the like in a case. In JP 2009-67140 A, a breather mechanism is provided in the accommodating chamber for the first electric motor so as to suppress a pressure change in the case. In addition, in order to suppress entry of oil, which is thrown up through rotation of a rotor of the first electric motor, into the breather mechanism, the breather mechanism is provided in an upper portion of the accommodating chamber for the first electric motor in a vertical direction.